Replication sets have been introduced. This new feature allows admins to
specify sets of tables that each node should receive changes on. It is now
possible to exclude tables that are not of interest to a particular node, or to
include only a subset of tables for replication to a node. Replication sets can
be used for data distribution, for data integration and for limited sharding.

The performance of global sequence voting has been greatly improved,
especially at higher node counts. It is now less likely for transactions to
fail because of global sequence exhaustion when the BDR group is under
significant write load.

The BDR source code has been split into two parts: a set of patches to
PostgreSQL 9.4 and a separate PostgreSQL extension. This helps streamline
work on integrating the features BDR requires into core PostgreSQL for
releases 9.5 and onward.

The patched PostgreSQL is now tracked in git branches prefixed with
bdr-pg/, mainly
bdr-pg/REL9_4_STABLE. The extension is now tracked in
git branches prefixed with bdr-plugin/, mainly
bdr-plugin/RELX_Y_STABLE (stable releases)
and bdr-plugin/next (current development tree).
All branches share the same working repository.

Prior releases of the BDR plugin were in the
contrib/bdr subdirectory of the patched PostgreSQL
source tree instead.